One traditional approach to precisely forming a pattern on a substrate using an exposure apparatus is to perform optical proximity effect correction (hereinafter referred to as OPC) on a pattern on a photomask for use in exposure.
An optical proximity effect is a phenomenon in which the shape of a pattern formed on a substrate, such as a silicon wafer, (hereinafter referred to as “actual pattern”) is different from the pattern on a photomask by diffraction or interference of light. OPC is correction of a pattern on a photomask to compensate for distortion occurring in the shape of the pattern caused by such an optical proximity effect. In general, a pattern on a photomask is corrected such that an actual pattern formed on a substrate resembles the original uncorrected pattern on the photomask, for example.
One known example of such an OPC technique is discussed in Japanese Laid-Open Patent Publication No. 2000-258893. This patent document discusses OPC performed when a contact for use coupled with other wiring is present in a termination or corner of wiring.